Special Report Questions For Larry

September 1, 2010 | By Larry Lyles

Readers Ask This Restoration Pro About Clear Coat Damage, Respirators, Welding and Shock Tower Repair.

Here’s What “Tack It” Means

When you’re working and say you “tack it clean” are you saying you use a tack cloth or a cheese cloth with some type of solvent on it?

George Wessel Wildwood,Missouri

I’ve been doing this for so long that I sometimes forget the terms I use may not be familiar to everyone else. So, to explain, I degrease surfaces and I tack surfaces

To explain further, degreasing is always a wet process. I degrease a surface using PPG DX330 Degreaser on a clean, lint-free cloth then wipe away the residue from the degreaser using another clean, lint-free cloth.

When I tack a surface, it’s a dry process. I use a resin-permeated cloth called a “tack cloth” to wipe the surface clean of any specks of trash the degreasing process may have left behind.

Degreasers are available at your local automotive refinishing supplier. Lint-free cleaning cloths and tack cloths can be found where paint products of any type are sold, including the local home improvement center.

Is This Respirator OK for Blasting?

I purchased a sandblaster to work on my 1985 GMC and would like to know what type of respirator you think is best for use when working with silica sand. I have a 3M paint respirator that I use when painting. Would this be OK?

Donald Walker Via e-mail

The 3M respirator you have will do the job just fine. I would also recommend using a hood along with the mask. It will help keep the sand off of your face and out of your hair.It Will also allow the mask to work better. For anyone who doesn’t have a good respirator try the Eastwood #34229 unit. It is made by 3M and designed for use when painting, but will do a good job when sand blasting as well.

I Was Wrong, You Can Use That Epoxy

In the July issue you say to not apply epoxy over DX1791. However, the PPG data sheets specifically list DPLF Epoxy

Primer as a compatible topcoat. Can you clarify? I have done three cars in my garage using these products over the last eight years and have had excellent results. No paint has fallen off the cars (yet). I’ve also attached photos of my “fleet.”

Tom Phillips Dripping Springs, Texas

Without whining and crying about the number of products I test in order to do these articles and using that excuse for screwing up, I’ll just say that the data sheets are correct. You can safely apply DPLF Epoxy over DX1791 wash primer.

What thrills me is that after all of the years I’ve spent telling people to read the “P”(product data)sheetsI can now confirm that the readers of Auto Restorer do indeed read the“P”sheets. Thanks To you and the other Auto Restorer Readers who brought this to my attention. By the way, your “fleet” is nice.

Editor’s note: Among Tom’s vehicles is the 1930 Ford Pickup seen below.

Should I Be Certified?

I am a faithful reader of Auto Restorer and I can’t recall seeing any information concerning hobby painters getting the EPA certification to purchase paint supplies starting sometime in 2011. Do you know anything about how this will work?

Charlie Mitchell Via e-mail

I know a little, and thanks for reading Auto Restorer. My information comes from my PPG supplier who advises that the certification will apply to commercial painting facilities and not the hobbyist.

To be considered a “hobbyist,” your paint purchases must be less than 10 gallons of paint and paint-related products per year. He also tells me that as the certification program now reads, paint suppliers cannot be forbidden to sell paint to hobbyists. To better define the 10-gallons a-year issue, that would roughly be the amount of paint, primer,sealer,reducer, hardener, and cleanup lacquer thinner required to refinish two vehicles.

To add my two cents’ worth, I would suggest that if your paint purchases fall below the 10 gallons per year threshold I would not seek to become certified. Should you elect to become certified, that means you would then be on the EPA’s radar and subject to following the standards set by them. I’m not telling you to scoff the law or pollute what little clean air we have left, I’m just telling you that as long as you are a hobbyist and working on your own vehicles and doing things correctly, that is, neverspray out in the open and never throw liquid waste material in the dumpster, and always allow it to completely dry out before discarding, I can’t see any reason to voluntarily attract the EPA’s attention.

Working With a Damaged Shock Tower

I am restoring a 1965 Mustang Coupe. While disassembling the car I noticed that the right front shock tower appears to be pushed inboard at the top. That made me suspect more damage so I did a thorough inspection and found several other issues up front that indicated the car had sustained damage sometime in its past. I can handle all of the other repairs that the car needs but I’m not sure how best to go about repairing the shock tower. Is it possible to take a long bar and basically pry the tower back into place?

Mike Skelton Belleville,Michigan

After reading your entire letter (that’s an edited version here) it would not be uncommon to find that the top of the shock tower had been pushed inboard due to the collision damage you described. With the aprons removed from the right side you should be able to use a long pry bar to return the tower to its original position.

You will need to know the correct cross measurement between the inboard bolts on both towers so that you will know how much to move the right tower. I’m thinking that measurement should be 30.5 inches. Once you have the tower moved you will also need to take diagonal measurements from the rear most fender mounting bolts out to each of the inboard shock tower bolts and when those measurements are equal and the distance between the towers is 30.5 inches, that should do it.

Another measurement I would take would be the length measurement of both frame rails. You need to be sure the right rail hasn’t sustained any crush damage that might have shortened it. What do you do if the rail is short by more than 1/2-inch? You’ll need to replace it.

Use a Welder, Not Adhesive, Here

I am restoring a 1968 Camaro with the help of your books, “Project Charger” and “Revive Your Ride.” I am going to replace the roof panel because of a poorly installed sunroof. I have the old panel off of the car and am now considering using 3M 8115 Panel Bonding Adhesive to attach the panel. Any thoughts or suggestions?

Dennis Zobitz Via e-mail

The first- and second-generation Camaros were constructed so that the roof panel is considered part of the unibody structure. Because of that I would weld the new roof panel on the car instead of using 3M 8115. That will ensure the structural integrity of the car. Something to consider is that the factory may have used brass to attach the roof panel to the quarter panels at the sail panels. Any brass found in this area will have to be removed by grin ding and cleaning the metal before welding.

Drill 5/16-inch spot welding holes around the perimeter of the panel, spacing the holes about three inches apart at the front and rear and two inches apart along the sides.

I like to screw down the entire new panel by placing #8 sheet metal screws every six inches or so around the panel. Start welding at each corner and work your way across the windshield and back glass openings before welding the sides.

Since this is a huge, flat panel, heat warping is a real probability. Use damp cloths to cool the panel as you weld and move from side to side of the car with each weld to distribute the heat and help keep things cool. If it sounds like I’m focusing on the heat problem, I am. Go slowly and keep the panel cool. That is the best way to reduce heat warping.

Removing Dust From New Clear Coat

The night after I finished putting the clear coat on my project we had a bad storm. When I checked the car the next day I found a sprinkling of fine dust on the hood, deck lid, and the tops of the fenders. I’m thinking I’ll now need to sand the finish and repaint.

Your thoughts? By the way, your “Curing Paint Problems” DVD is right on target and has been a great help.

Tom Watts Via e-mail

Thanks, glad the DVD helped. If the storm hit a couple of hours after you applied the clear, hopefully the outer layer had time to film over and the dust you are seeing is just sitting on the surface and hasn’t sunk into the clear coating.

My suggestion is to let the clear cure out for at least two days then gently wash the car before wet sanding the clear using 1000 grit. I stress “wet and gently” because dust is like sandpaper and it can and will scratch the surface. Use running water as you sand and hopefully the dust will come right off and leave you with a clean surface that can be compounded.

If the dust has filtered down into the clear it most likely will not have penetrated beyond the top layer. In that case wet sand the surface using 800 grit. The 800 will remove a lot of the clear so be careful not to over sand and expose the color coat beneath.

After sanding you can apply more clear. I would apply at least three coats, four if you have enough product.

Be aware that applying additional clear over a sanded clear coat can be tricky. You are now working with an extremely smooth surface and the clear will have a tendency to want to run and sag. Spray your coats a little faster (as shown in the “Curing Paint Problems” DVD) to produce a thinner film and give each coat at least 30 minutes to cure before adding the next coat.

Editor’s note: For moreon Larry’s books and DVDs, visit his Web site: lplbodyworks.com.

Working With Matte Black

I recently discovered the matte black look and am contemplating using this product to spray my 1969 Mustang.

My thought is to spray the body of the car in matte black and spray the center section of the hood in a gloss black. This would be in contrast to the way the car was painted from the factory, with a matte black section on the hood, and gloss black on the body.

My question concerns the difficulty of spraying this type of finish and whether I need to do anything special to apply and care for this type of product. I’m also wondering how perfect the body will need to be since the matte finish won’t have a shine.

Dan Boucher Via e-mail

I reviewed a urethane-based matte black finish made by Kirker back in April 2007. I really liked the finish and I especially liked the fact that the finish was urethane and would withstand exposure to UV radiation. TheKirkerfinish sprayed like any other urethane-based single stage finish. I applied three medium wet coats to achieve good coverage and the results were nothing short of excellent.

Asto how perfect the surface should be, I would think getting the car as smooth as possible will give you better results.

Even though the gloss will be absent, any imperfections will definitely show through. I would also lean toward keeping any wax or compound away from the finish. I don’t think wax or compound will result in staining, but it might improve on the gloss factor and that would defeat the purpose of the technique

Tips for Welding With Weld-Through Primers

I need to do a small rust repair on a fender and weld in a patch panel. I’ve used weld-through primers in the past on this type of repair but have found welding through the primers very difficult. Is there a trick to this?

Wallace Wheeler Dallas, Texas

Yes, there is a trick. Weld-through primers are designed to withstand the heat of welding, so striking a welding arc through this type of primer can indeed be difficult.

My method is to first lightly sand the area to be primed. Next, I drill or punch out the spot welds. (Editor’s note: For more on working with spot welds, see Larry’s article on page 22 of last month’s issue.)

After that, I apply the primer to both panels being joined.

Once I’m ready to weld, I hit the spot weld holes with a wire wheel on a small angle grinder. This cleans the primer from the spot weld area, or any other area I need to weld, and leaves me with a clean surface for welding.

Of course, the last step in the process, after everything has been welded and the welds have been ground smooth, is to coat the repair with epoxy.